In many mass production processes known in the prior art, there is a need to subject products to process steps while they are being transported. For example, in baking bread, the loaves of raw dough must be "proofed", or allowed to rise, after formation and before baking. Similarly, after baking, the loaves must be allowed to cool before wrapping. Thus, there is a need to transport the individual loaves in large quantity while subjecting them to a flow of air in order to preserve the continuity of the mass production process. The need for the free circulation of air is particularly important where food stuffs are to be frozen after processing. Similarly, in many chemical processes, product units must be subjected to a flow of fluids while being transported in large quantity.
It is known in the prior art to use conveyor belts of various constructions to transport product units for processing. However, such prior art conveyor belt constructions have been difficult to maintain in the required clean and sanitary condition, or they have been complicated and expensive to manufacture and in either case, they have been difficult to drive. Thus, a simple continuous surface belt does not provide for the circulation of fluids about the product units, is difficult to clean and sterilize and does not provide for positive drive. The provision of apertures through the belt will enable the circulation of fluids therethrough for processing and cleaning or sterilizing purposes but will further complicate the application of driving forces to the belt.
It has been proposed in the prior art to attach drive chain to an apertured belt in order to provide for the application of drive forces to the belt. However, the difference in materials between the chain and the belt make it difficult to form and maintain a secure mechanical interconnection therebetween, particularly where the belt is subjected to temperature fluctuations in use or cleaning. In addition, the attachment of chain drive means complicates the cleaning and sterilization of the composite structure.
A closely related alternate structure proposed in the prior art is the provision of transversely extending apertured support elements mounted on each link of a drag chain or between corresponding links of a pair of parallel drag chains. This structure avoids the interconnection difficulties associated with the attachment of a chain to a belt but it presents additional difficulties in that the separation between adjacent support elements tends to collect product fragments thereby presenting additional cleaning and sterilization problems. In addition, the fabrication of the structure is complicated and expensive due to the number of elements involved which must be interconnected.
For the above reasons, it has been proposed in the prior art to construct a conveyor belt of a multiplicity of link elements, usually of metal, interconnected by a plurality of transverse pins. Such a structure is inherently foraminous providing for the circulation of fluids therethrough in use and cleaning. In addition, such a structure is inherently suited for conventional chain drive by the engagement of the teeth of sprocket wheels with the transverse pins. However, due to the multiplicity of its parts, the structure is expensive and complicated to construct and presents excessive difficulties in cleaning and sterilization, because of the interconnection between the parts.
This invention is directed to overcoming the shortcomings of the prior art as set forth above.